Crna Mechka

I just recently noticed a strange sound coming from the exhaust area of my car and it only happens when the car is on.

Like the title says, it is a sort of hissing sound. Sounds kinda like a tire with a small puncute slowly deflating with random breaks once every few seconds.

Becaus of the area the sound is coming from, I originally thought it to be the rear left tire deflating but after checking for the noise when the car is off the hissing seems to be non-existant.

Any ideas? I'm stumped.

samaritrey

I think someone once said they had something similar and it was the fuel pump or something fuel related.

Silver C

Any other symptoms besides the sound?

Glyn M Ruck

People say the fuel filter can hiss. I have never experienced this.

Hisses I have experienced were Cat monolith breakup where a chunk fell off & partially blocked the exhaust system causing wheezing & hissing if you revved the car.

Crna Mechka

Thanks for your replies gentlemen.

I haven't noticed anything unusual besides the hissing symptom, only the MPG rating dropping a bit.

I was getting something like 22mpg in the city last month, now I'm getting anywhere between 15-20mpg at most.

Haven't made any modifications under the hood either, and have been/still using only Mobil 1 93 octane ($4.10/gallon in MA right now).

Like I mentioned, it only happens when the car is on so I assume (like samaritrey mentioned) that it may have something to do with the fuel pump.

Seems to be in that general area.

Can anyone shed some more light on this?

Crna Mechka

Not sure if this relates to the symptom I'm experiencing mainly because the hissing sound commences as long as the car is running - I don't think it makes a difference if I'm revving the engine or not. I may be wrong though, hard to tell.

Crna Mechka

Now that you ask, I actually noticed a clunking sound coming from the engine bay area the other day when I was coming to a stop at a light.

I've only ever heard this noise one time and that was it, so I guess I'm not too worried about it as of now.

I did a search on it, and most of the results that came up had to do with the belt tensioner on the Kompressor's going bad.

TruTaing

Exhaust leak? :x

Crna Mechka

That would be a pain in the ***. You think I should just take her to an exhaust specialist to look at?

C230 Mulac

+1 thats what i was thinking. you can prob get a good muffler shop to patch it up for you but if you want a permanent fix you would need a new muffler or whatever piece was leaking. you could always use this as an excuse to get a new exhaust though

Crna Mechka

You make a very valid point about this being a good opportunity to get a new exhaust but unfortunately I'm only planning to keep her as far as the end of this summer so an investment like that is not worth the cost right now.

When you say, a "good muffler shop" - do you mean a place like Meineke or an indy who specializes in Mercs?

I'd like to just get this patched up for now.

C230 Mulac

you would have to go to an exhaust shop. if you go to an indy shop, the only thing they would really be able to do is replace the entire muffler or pipe that is leaking, they usually don't do patching and that type of stuff.

as for meineke, midas, etc. it depends on the location for which is good or not. some places they are pretty good and others they might suck. i would see if you know anyone who has gone to them and ask or find some reviews online. otherwise, you could probably look for a local exhaust shop that has a good rep.

Crna Mechka

Thanks for the tips man, I really appreciate it. Was going to make a trip to Meineke but after speaking with a buddy of mine he suggested a local shop that won't try to rip me off just because I drive a Benz, so paying them a visit soon

Boom vang

hissing = small air leak in exhaust. Check unions (between flanges ) and small hole/crack

C230 Sport Coup

You might need a new Cat.
Go to muffler shop, but find a small independent place not Midas.
They'll tell you if you have a leak, clogged cat or both.

C230 Mulac

no prob dude, the small guys are definitely the best. places like midas and meineke are almost as bad as the stealership

Carsy

Partially plug the exhaust with a rag which creates a higher backpressure. If you have a leak you should be able to hear it more clearly & find the location.

Don't burn yourself.